FCC approves first wireless power at a distance charging system | Hacker News Reader

FCC approves first wireless power at a distance charging system

engadget.com

57 pointstempay34 comments

For some more details, you can look at there press release[0]. It says the device "can deliver power via radio frequency (RF) energy to WattUp-enabled electronic devices at a distance of up to three feet".

You could also listen to their conference call[1] where they "review the FCC certification details in greater depth and answer questions". I haven't gone through it, though.

[0] https://ir.energous.com/press-releases/detail/596/energous-r...

[1] https://services.choruscall.com/links/watt171227.html

Blog with some analysis and a lot of older info on Energous:

https://liesandstartuppr.blogspot.com/2017/12/energous-and-f...

Previously on HN:

CES announcement (3 years ago)

https://news.ycombinator.com/item?id=8860644

Apple reported working with Energous (1 yr ago)

https://news.ycombinator.com/item?id=12508409

... and shareholders were richly rewarded: https://www.bloomberg.com/quote/WATT:US

(the stock was up 168.10% on the day)

Also first time since IPO that it's above the IPO price. Right on time for the first employees to cash out.

Everybody wins!

I can't seem to get any info on how much power is actually transmitted/received... it's hard to beat the Inverse Square Law.

Previous articles claim 4 watts at 5 feet in the 5GHz ISM band via phased array antennas.

I'm as skeptical as you.

no it's not, you use a directional antenna or phased arrays and beamforming (which is what they're doing).

It looks like the FCC approval pertains to a device delivering ~10W at a distance of 0.5m in the 900MHz band. https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm...

So what makes the radio waves magically drop off the face of the earth after .5m? And who allows 40 dBm (much more if we're talking at .5m distance) in an ISM band?

I mean, that test report is making a lot of assumptions and setup constraints that are now magically not present in the video..

Yes, I have been trying (unsuccessfully) to get my head around how the test setup would translate into a practical application. And that the certification appears to violate the FCC's own 30dBm power limit in the 900MHz ISM band. Very strange.

The ISM field strength levels here are defined in 47 Part 18.305. they are measured in an anechoic chamber and inverse square law scaled to the field strength at the stated distance.

Source: I used to work with RF lighting devices, which need to meet the levels of 18.305(c), and were usually tested the same way in pre-compliance before final OATS testing.

>>>... device delivering ~10W at a distance.

I'm reading it very differently. ~10W is the power of the transmitter, the bit that the FCC actually cares about, not the energy delivered to the target device. With all the inefficiencies and losses, I think they are far below 1w in actual delivered power.

From the title: "from 3 feet away."

From article and press release: "of up to three feet."

As usual, the devil is in the details: one angstrom would satisfy the "up to three feet" claim as well.

I also would like to see the actual throughput. Wasting say 10 watts to get 1 watt of available power because one doesn't want to use a cable seems pretty lame to me.

> The transmitter converts electricity into radio frequencies, then beams the energy to nearby devices outfitted with a corresponding receiver.

Just curious, any thoughts on radiation impact to people?

Radio waves have been extensively studied for over 100 years, and there have been numerous studies trying to ascertain if they cause health problems in humans or other animals.

"Radiation" is a bit of a scary word, the general public thinks of nuclear radiation. Even though radio waves can be called radiation they cannot cause harm in the same way that UV radiation causes cancer, for example. Radio waves can heat things up, and can even cause burns, but you'd need to do something incredibly stupid like disassemble your microwave, or stand in front of a primary radar dish. By comparison, the word "radiation" is often used to refer to ionizing radiation which can destroy molecules in your body, even at low power.

The battery charging works because the antennas are very efficient at picking up radio waves of a specific frequency, unlike humans, which do not make very good antennas. I am personally skeptical about the power efficiency of wireless battery charging but radio waves are fairly benign to those of us made out of meat.

EDIT: I didn't consider dielectric heating (https://en.wikipedia.org/wiki/Dielectric_heating). Seeing as how microwave ovens have 500W rating on the low end, I assume heat generated by 10W source can be dissipated fast enough that proteins don't get denatured even if it's directed at a small area of the body.

Most energetic photon in radio frequencies has wavelength of 1mm and energy of 0.00124eV (http://www.photonics.byu.edu/fwnomograph.phtml) I think. Would just pass through a single cell as cell is much smaller than the wavelength. And 0.0012eV is really small amount of energy. "Van der Waals bonds are weak bonds with a dissociation energy of about 0.01 eV" (http://lamp.tu-graz.ac.at/~hadley/ss1/crystalbinding/bonds/b...) I wouldn't expect it to do anything cellular/molecular level.

Not really a biology person so don't know if there's some effect on aggregate of cells on the millimeter level that could be harmful. Human body's electrical resistance inside is high and through skin is higher so I don't expect much effect on that scale either?

I'm no biology person either, but in terms of photons, I do find these interesting;

'Biological tissues typically produce an observed radiant emittance in the visible and ultraviolet frequencies ranging from 10−17 to 10−23 W/cm2 (approx 1-1000 photons/cm2/second).[1] This low level of light has a much weaker intensity than the visible light produced by bioluminescence, but biophotons are detectable above the background of thermal radiation that is emitted by tissues at their normal temperature.

While detection of biophotons has been reported by several groups,[2][3][4] hypotheses that such biophotons indicate the state of biological tissues and facilitate a form of cellular communication are still under investigation,[5][6] and claims that biophotons are responsible for physical healing are unsupported. Alexander Gurwitsch, who discovered the existence of biophotons, was awarded the Stalin Prize in 1941 for his mitogenic radiation work.[7]'

https://en.wikipedia.org/wiki/Biophoton

What are some situations that:

1. Has a device in question draw less than the wireless charging could input (both practical and theoretical). Obviously, unless it's OK with the device still running in a "net negative" state, you'd want the wireless charging to at least cover the device's use.

and

2. Necessitate motion or usage, or in other words, have the item not be at rest The idea here is that if the device primarily sits, there's little advantage to wireless charging

- Power tools, for example cover (2), however not (1).

- An iPhone may cover (1), but not (2).

Can't uBeam already do this??

https://www.usatoday.com/story/tech/news/2017/06/01/ubeams-m...

No. Perry's scam utilizes ultrasound, and it works as well as you would expect if you do the math, i.e. pretty much not at all.

Is it normal to feel a tad bit scared of wireless charging?

I share the same concerns. I wasn't able to find enough details to support their claim about "safe, small, and focused amounts" of power.

Until it's been independently tested and used in the real world for a while, it makes sense to be suspicious of any form of energy transmission or storage. Energy is dangerous.

Just don't let the suspicion last long enough to become superstition.

There is considerable wisdom in this response.

Thank you, but be careful. It sounds wiser because that last line is so pithy.

Sounds really cool! I can't wait to charge my phone just by setting it on my nightstand at the end of the day. And my smart watch, and my headphones.

You can already do that? Apple has a charging pad for the iPhone X, watch and earpods.

I had a Nexus 5 a couple of years ago that could do that and I am sure there have been phones way before that with induction charging.

Another Wattup company with tech specs in the faq http://energous.com

What's the proper way to flag these obvious PR pieces with no technical information at all?

As with any submission you think is not appropriate for HN, use "flag".

Start by not assuming that the poster is endorsing it; maybe they just want to share something relevant and stupid being spread around. Maybe it’s a discussion piece, centered on the flaws in the piece.

If you have enough karma there's a "flag" button, but I don't see any reason to flag PR pieces that have useful information in them

Well, it's "useful" to know the FCC actually approved this, but it's at the barest end of that. But this piece doesn't include even the barest of technical details.

If it included things like which band (5GHz), what power (claimed to be 4 watts at 5 feet--how does that get by FCC?), or any other technological point, I probably wouldn't be so annoyed.

As it stands, this is quite obviously a stock pump PR piece, and this company has a history of doing this since at least 2014.

I do have a flag button, but I normally reserve that for things which are ferociously offensive rather than just scummy.

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